i just stripped a bunch of caulking, roofing tar, bondo, fiberglass, and a million layers of paint, from a small open aluminum boat. now i have a bunch of loose rivits and some decent cracks. im guessing it wouldnt float with me in it for more than 15 minutes. so how do i fix the leaky rivits and cracks without welding or replacing rivits (i just dont see replacing them working very well). but before hand it did very well and barely leaked at all. and i dont have the option of getting another one. so how do i fix it cheap. what do i use and how do i use it.
Repair the ship because of the complexity should be left to experts. Not very clever attempt was the time if you are not qualified.
There is no cheap long term fix. the rivets can be reseated or replaced try a punch on both side. The cracks have to be welded. or sand and coat with a rubber base water proof sealer like used on airboats. Fiberglassing the entire bottom but if it flex's it will leak.
We repair boats on occasion at my shop. We use an aluminum patch and Tig weld it in. That's really the only correct way to repair it . Its also a patch the will last a long time. The reason we use a patch is because most of the holes that get in these boats are a gradual wearing on the aluminum from running them up on the banks of lakes and rivers.
Aluminum Boat Hull Repair
You just pulled off the cheap repair - that had failed or you wouldn't have had to. As the problem wasn't fixed correctly the first time it now is that much harder to repair. The rivets are structural, if they are completely stuffed, and the original holes far too spread out you are looking at riveting Through stainless washers, or even a sandwich of aluminium sheet, with sikaflex or similar between as a gasket - silicon is no good. If you don't weld or rivet the repair you are not going to return the hull to original strength. No amount of gloop and caulking can make a boat - or boat hulls would be built from it. I have seen marine ply used to repair and alter aluminium pressed hulls - but really there is not much difference in cost and effort. If the splits are really big you might consider investing in a small MIG welder to do repair patching - but if you build up one area too much it will only focus the stresses of that section elsewhere, probably leading to quick failure in adjoining areas. If you prep the hull yourself and clearly mark the areas that need welding, take the hull inverted to an alloy welder it will only cost a few tens of dollars to get them buzzed up - it is the prep time that costs with any tradesman. So the cheapest repair is to do it right using rivets and aluminium plate and stainless washers and weld as needed. You should get a two handed rivet gun - the one handed ones are really hard on the hands when they pop. You also will require high quality drill bits and goggles - be prepared to break a couple of bits should the metal move or the bit catch on an angle. I always buy a heap of the double end type and if I break one, flip it and keep going. It is perfectly normal practice to go up a size in rivet to get a firm contact, I also use Duralac to prevent electrolysis between the slightly different alloys. Good luck.
